Period

Events

1173-1178

More than 3 floors of the tower had built when it started leaning

1178-1272

Construction of tower was interrupted and consolidation of the soil took place

1272-1278

Stage construction to 7^th floor was completed

1278-1360

Consolidation of the soil took place

1360-1370

Construction of bell chamber took place

1859

The inclination angle of the tower was measured to be about 5.5 degrees